Transcript BaBar Fast Monitoring

JAS in BaBar Online Monitoring
V. V. Serbo*, for the BaBar computing group
* Stanford Linear Accelerator Center, Stanford, CA 94309, USA.
Abstract:
•Written entirely in Java – really portable.
•Originally targeted at offline analysis, but also used extensively for online
monitoring.
•Rich, easy to use GUI.
JAS GUI
•Can view trees, plots, HTML pages
with embedded active objects.
•Built-in editor/compiler.
•Local and Client-Server Operation.
•Can send analysis code to the data
and ship back only the results.
•JAS info, demos, downloads:
http://jas.freehep.org
Tree area
provides
access to
analysis
objects. Each
item has
popup menu
and doubleclick action.
Pages can display
histograms. User can
control layout, add,
remove plots.
In order to insure the quality of collected data, hundreds of monitoring histograms are filled during the BaBar run. Babar is using JAS (Java Analysis Studio,
http://jas.freehep.org ) as a means of presenting online monitoring histograms to people on shift. JAS is an interactive analysis application, written in Java, with
a rich GUI and ability to work in client/server mode as well as a stand-alone application. Three-tier approach is used, with an intermediate server that acts as a
gateway between BaBar CORBA-based distributed histogram facility and JAS RMI-based client/server communication protocol. The server is implemented in
Java and uses the JAS online monitoring API. Histograms are displayed in the JAS client using HTML pages with embedded live and reference plots for each
detector subsystem. The HTML pages also provide descriptions of the plots, instructions and contain hyperlinks to additional pages with more detailed
diagnostic histograms.
L3
Built-in HTML viewer
with embeddable
“active objects” (plots,
buttons, etc.).
Plot Widget,
shows data
in real time,
optimized
for fast
refresh
performance.
Features of JAS Plots
•Plots update in real time.
•Data for plots can be local or remote (use
Java RMI to connect to JAS Data Server).
•Rich variety of styles for 1D and 2D plots.
•Integrated with simple fitting capability.
•High quality print output and export of plots in a variety of formats,
including PS, EPS, PDF, SVG, GIF, PNG.
•Live plots can be embedded in the HTML pages.
•Overlays: data from several independent sources can be displayed in one
plot.
~150 Hz
BaBar Online Monitoring
•During the run hundreds of monitoring histograms are
filled using part of BaBar data.
•Live histograms are accessible through the BaBar DHP
CORBA Server.
•DHP – Distributed Histogramming Package in BaBar
framework.
•Jas Interface Server:
- Connect C++ and Java world
- “Concentrator” for JAS clients
- Cashing of data
•BaBar runs several DHP servers that provide live and
reference histograms.
•Two Jas Interface Servers: one for people on shift and
one for everybody else.
L1: ~1 kHz
~5 %
100 %
LiveFastMon
DHP Server
L3 DHP
Server
( C++ )
( C++ )
JAS Client
( Java )
CORBA
Archive
JAS Interface
Server
RMI
( Java)
JAS Client
( Java )
Monitoring BaBar data quality
•During the run: HTML pages with
Live plots
Reference plots
Instructions for people on shift.
•Archives: Monitoring Histograms are archived at
the end of each run.
Future:
•JAS3 (http://jas.freehep.org/jas3) uses a highly modular component based framework, into which
various analysis modules can be plugged.
•Can be customized for a particular problem domain by addition, replacement or removal of modules.
•Relies on Java FreeHEP Library (http://java.freehep.org).
•Scripting support (Jython, pnuts).
•Some of the existing modules: WIRED (http://wired.freehep.org), JAS Plotter, JAIDA – Java
implementation of AIDA (http://aida.freehep.org).
•BaBar Monitoring applications will become JAS3 pluggable modules.
•More features, less code, shorter development cycle – rely on functionality of other JAS3 modules.
•URL-like protocols to access remote data:
–Full description of data location
–“Alias”: location relative to the server name
–Can use same access mechanism for interactive access and in HTML pages.